Why she might win: As a rare woman to dominate an action thriller, Chastain's steely-eyed determination is as riveting as that of any macho man, but with a distinctly female sensibility.

Why she might lose: Controversies over the film's depiction of torture could work against her.

Jennifer Lawrence, 22, in Silver Linings Playbook

Her role: Tiffany, a feisty widow who carries plenty of her own baggage as she rocks Bradley Cooper's bipolar world.

Oscar history: Nominated for best actress as Ree Dolly, a backwoods teen who must outwit her unsavory Ozarks clan to save her mother and young siblings in 2010's Winter's Bone.

Why she might win: Lawrence has proven her star power in action fare like The Hunger Games. But here she delights as a throwback to the kind of smart-mouthed heroines that used to abound in screwball comedies decades ago.

Why she might lose: At her age, many other opportunities to collect gold will likely lie ahead.

Quvenzhane Wallis, 9, in Beasts of the Southern Wild

Her role: Hushpuppy, a 6-year-old living a nearly feral existence in the Louisiana bayou, who endures alongside her ailing father.

Oscar history: It starts today.

Why she might win: This untrained youngster's mesmerizing performance is a one-of-a-kind wonder that won't be repeated soon.

Why she might lose: The youngest nominee ever in this category - a distinction previously held by a then-13-year-old Keisha Castle-Hughes of 2003's Whale Rider - might have to wait until she ages into double digits to have a real shot at the prize.

Naomi Watts, 44, in The Impossible

Her role: Maria Belon, a British tourist at a Thai resort whose family is torn apart when the 2004 tsunami strikes.

Oscar history: Nominated for best actress as a widow who unknowingly falls for the recipient of her dead husband's heart in 2003's 21 Grams.

Why she might win: There's nothing like a beautiful actress suffering on screen to excite voters, and a soaked Watts did just that.

Why she might lose: The film has yet to strike a chord with most moviegoers.

Emmanuelle Riva, 85, in Amour

Her role: Anne, an elderly music teacher, whose devoted husband tends to her needs in their cloistered apartment as her health deteriorates.

Oscar history: The French legend is best known as the romantic lead of 1959's Hiroshima Mon Amour, which was nominated for a screenplay Oscar.

Why she might win: As the oldest lead actress nominee ever, Riva gives a master class of nuanced acting with her devastating portrait of a dying woman coping with her inevitable fate.

Why she might lose: Foreign-language performers are often are passed over.